Traditionally, visual acuity has been measured using eye charts, in which subjects interactively provided vision-related information by reading characters of various sizes from the eye chart. The refractive error of the eye has traditionally been determined by having the subject recursively view objects through various sphero-cylindrical lenses, and selecting the combination of lenses that provides the clearest image. While such acuity and refraction measurements are still widely used, they provide only gross measurements of the visual system.
Unlike refraction, ocular aberrometry provides greater details with reference to the refractive properties of the eye. In ocular aberrometry, the refractive properties of the eye are measured using various lenses and projections, typically sampling multiple points across the pupil rather than a single measurement as performed during refraction, thereby providing more detailed information on higher-order optical anomalies. The aberration information provided by ocular aberrometers is designated herein as “ocular wavefront error.” Examples of ocular aberrometers and ocular aberrometry are disclosed in U.S. Pat. Nos. 5,777,719, 6,095,651, and 6,511,180, which are incorporated herein by reference in their entireties.
While ocular aberrometers provide detailed information on the optical characteristics of the eye, these devices usually provide no information with reference to the neurological pathways between the eye and the brain and they are not capable of localizing the retinal plane preferred by the patient. In other words, the integrated visual pathway between the eye and the brain can introduce another transfer function, which is undetectable by ocular aberrometry.
In order to address these deficiencies, a technique known as visual aberrometry has been developed, in which the patient's preferred retinal plane is localized and the effects of the neurological pathways are taken into account by combining subject feedback with the physio-optical characteristics of the eye. The aggregate effect of the neurological pathway in combination with the characteristics of the eye is referred to herein as “neuro-ocular wavefront error” or “neuro-ocular wavefront data.” Examples of visual aberrometers are described in greater detail in U.S. Pat. Nos. 6,000,800 and 6,099,125, which are incorporated herein by reference in their entireties.
Visual aberrometry, and the acquisition of neuro-ocular wavefront data, is still relatively new and continually improving. Along with the continued development of visual aberrometry, there is corresponding effort to exploit the full potential of visual aberrometry.